Modular or mobile home, with or without metal side railings in same or separate packages, steel, completely disassembled, having a density of 20 pounds or greater per cubic foot, Applies only on steps or stairs such as modular or mobile home steps or stairs having one step in addition to a platform, or two or more steps with or without a platform. Density must be shown by the shipper on the bill of lading and shipping order at time of shipment. If density is not shown and shipment is inadvertently accepted, charges will initially be assessed under the provisions of item 179310, naming 'Steps or Stairs, modular or mobile home, NOI.' Upon satisfactory proof of actual density, freight charges will be adjusted accordingly. In boxes